The present invention generally relates to superconducting devices, and more specifically, to a microwave switch such as a lossless, variable transmission-reflection switch that is fully controlled by the phase of a microwave drive.
A microwave switch or radio frequency switch is a device to route high frequency signals through transmission paths. RF and microwave switches are used extensively in microwave test systems for signal routing between instruments and devices under test (DUT). Incorporating a switch into a switch matrix system enables the system to route signals from multiple instruments to single or multiple DUTs. This allows multiple tests to be performed with the same setup, thus eliminating the need for frequent connects and disconnects. The entire testing process can be automated, which increases system throughput in high-volume production environments. Like other electrical switches, RF and microwave switches provide different configurations for many different applications.
Superconducting quantum computing is an implementation of a quantum computer in superconducting electronic circuits. Quantum computation studies the application of quantum phenomena for information processing and communication. Various models of quantum computation exist, and the most popular models incorporate the concepts of qubits and quantum gates. A qubit is a generalization of a bit that has two possible states, but can be in a quantum superposition of both states. A quantum gate is a generalization of a logic gate, however the quantum gate describes the transformation that one or more qubits will experience after the gate is applied on them, given their initial state.
The electromagnetic energy associated with the qubit can be stored in so-called Josephson junctions and in the capacitive and inductive elements that are used to form the qubit. In one example, to read out the qubit state, a microwave signal is applied to the microwave readout cavity that couples to the qubit at the cavity frequency. The transmitted (or reflected) microwave signal goes through multiple thermal isolation stages and low-noise amplifiers that are required to block or reduce the noise and improve the signal-to-noise ratio. The microwave signal is measured at room temperature. The amplitude and/or phase of the returned/output microwave signal carry information about the qubit state, such as whether the qubit is at the ground or excited states or at a superposition of the two states. A microwave switch can be utilized in the communication of quantum signals associated with qubits, qubit gates, and quantum communications in general.